This project focuses on an enduring problem in the study of speech: How are perception and production linked? The specific aims address the process of speech perception while listening and talking. When individuals speak, the sound of their own voice is a powerful influence on the accuracy of fluent speech and is a major force in learning to speak. This grant proposal asks whether "listening to yourself" (feedback perception) is different from listening to others (communicative perception). The key to our work is a real-time signal processing system that permits perturbations of auditory feedback of speech with a very short time delay. The formant shifting system that we have implemented has an iteration delay of less than 1 ms, and the duration of the analysis window is chosen to provide an effective delay of approximately 9.5 ms. Thus, talkers in our studies produce utterances but hear spectrally modified versions of them through headphones as they speak. Three separate projects tackle different aspects of our question. The first project tries to determine if the operational principles (e.g., sensitivities, category boundaries) are the same for feedback and communicative perception. The second project uses short-term learning or adaptation paradigms to see whether the two types of perception are functionally linked. If one type of perception is changed, does it influence the other? The final project involves mapping the neural correlates of speech perception. We use our innovative signal processing system to study the network of brain regions involved in processing auditory feedback of speech. By focusing on the impact that producing speech has on the perception of speech these studies will add significantly to our understanding of the psychophysical, cognitive and anatomical relationships between speech perception and production. The studies proposed here also are relevant to a range of clinical populations (e.g. schizophrenia, fluency disorders, hearing impairment) in which the relation between perception and production is an ongoing research and intervention focal point.